1. Field of the Invention
The present invention relates to the structure of a hand for an industrial robot, and more particularly, relates to a robot hand of a type in which the number of fingers can be changed in order to adequately grasp a workpiece, taking into account a change in the shape of the workpiece. That is, for example, the number of fingers on the robot hand can be changed from three to two when the shape of the workpiece is changed from round to square or polygonal.
2. Description of the Prior Art
Industrial robots are used for conducting various types of operation under the control of a robot controller, and conventionally, must use different types of hands depending upon the change in the type of operation. Therefore, an industrial robot is usually provided with a set of several different robot hands, each hand being adapted for only a predetermined type of operation to be carried out by the industrial robot. Thus, in response to each change in the type of operation, the robot hand attached to the industrial robot is changed to another type of hand. For example, when the industrial robot is used for conveying workpieces from one position to another, a robot hand having three opening and closing fingers is employed if the workpieces are round. On the other hand, if the workpieces are square or polygonal, a robot hand having two opening and closing fingers is used.
This changing of one robot hand for another is conducted under the control of the robot controller, which is programmed for this hand-changing operation before placing the industrial robot into operation. However, the scope of application for industrial robots has become very much wider and, thus, the frequency of changing the robot hands has increased, making the programming of the controller for the hand-changing operation extremely complex.